Submitted to: Molecular and Cellular Proteomics
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 8/5/2003
Publication Date: 10/1/2003
Citation: Choi, B., Chitwood, D.J., Paik, Y. Proteomic changes during disturbance of cholesterol metabolism by azacoprostane treatment in caenorhabditis elegans. Molecular and Cellular Proteomics 2: 1086-1095. 2003. Interpretive Summary: A major problem facing U.S. agriculture is the lack of control measures for nematodes, i.e., microscopic worms that annually reduce U.S. agricultural productivity by ten billion dollars. One approach to developing new control methods is to disrupt biochemical pathways that occur only in nematodes, such as the nematode sterol pathway. Sterols are chemical compounds found in the cells of plants and animals; cholesterol is the most common sterol in animals. In previous research, ARS scientists showed that some chemical compounds that disrupt sterol biochemistry in nematodes destroy the ability of nematodes to grow and reproduce. This paper describes cooperative research with scientists in the Republic of Korea. The research team attempted to learn how disruption of sterol metabolism actually kills nematodes. Specifically, the team examined the effects of one disrupter on the synthesis of different kinds of proteins by nematodes. The results indicated that treated nematodes contained low levels of some important proteins usually abundant in the nematode body wall and others involved in transporting fats inside nematodes. The results are significant because they indicate that nematode sterols regulate the synthesis of important proteins by nematodes. This information will be utilized by scientists interested in developing safe, innovative strategies for managing plant-parasitic nematodes.
Technical Abstract: Although nematodes like Caenorhabditis elegans are incapable of de novo cholesterol biosynthesis, they can utilize nonfunctional sterols by converting them into cholesterol and other nematode sterols. Blocking of sterol conversion to cholesterol in C. elegans by azacoprostane treatment causes serious defects in germ cell and cuticle development, growth, and motility. To establish a biochemical basis for these physiological abnormalities, we performed proteomic analysis of azacoprostane-treated worms. Compared to controls, treated C. elegans contained lower levels of proteins involved in collagen and cytoskeleton organization, such as protein disulfide isomerase, beta-tubulin and Nex-1 protein. A few enzymes involved in energy production were also reduced, as were the lipoproteins vitellogenins-2 and -6, indicating that azacoprostane-induced sterol metabolism disturbance is tightly coupled with suppression of lipid transfer-related proteins. In contrast, competitive quantitative reverse transcriptase PCR showed that the transcriptional levels of vit-2, vit-6 and their receptors (rme-2 and lrp-1) in drug-treated worms were 3- to 5-fold higher than those in the untreated group, suggesting a presence of a sterol regulatory element binding protein (SREBP)-like pathway. Therefore, many physiological abnormalities caused by azacoprostane-mediated sterol metabolism disturbance may be exerted at least in part through an SREBP pathway in C. elegans.